reductive acetyl CoA pathway

Unlike the reverse tricarboxyclic acid cycle (rTCA), the 3-hydroxypropionate cycle, and the Calvin cycle (RuBP), the reductive acetyl CoA pathway (rACA) is a noncyclic pathway.

The path has both a methyl and carbonyl component. One CO2 is captured on a special tetrahydrofolate cofactor and reduced to a methyl group. The other CO2 is reduced to a carbonyl group (C=O) by carbon monoxide dehydrogenase, and this enzyme-bound carbonyl group is combined with the methyl group to form acetyl CoA by a collection of enzymes termed the acetyl CoA synthase complex. The pathway seems to require hydrogen gas as the electron donor and it is very efficient, requiring only 4H2 per acetate formed.

Organisms that employ rACA include acetogens, which are microbes that generate acetic acid from hydrogen (Clostridium thermoaceticum, Acetobacterium woodii), methanogens (Methanobacterium thermoautotrophicum) and most autotrophic sulfate reducers (Defulfobacterium autotrophicum).

Table ~ Comparison Photosynthesis Respiration : Table ~ Comparison Plant Bacterial Photosynthesis : Table ~ comparison of C-3, C-4, CAM plants : Table ~ Photosynthesis Overview : Microtextbook Carbon Assimilation ::: image_Calvin cycle : image_reductive tricarboxylic acid cycle : image_reductive CoEnzymeA cycle : image_3-hydroxypropionate cycle :: Saccharomyces cerevisiae carbon monoxide dehydrogenase pathway : Arabidopsis thaliana carbon monoxide dehydrogenase pathway : MetaCyc reductive acetyl coenzyme A pathway :